1. Field of the Invention
The present invention is directed to providing new and improved diffusion transfer process photographic film units adapted to provide, as a function of the point-to-point degree of photoexposure, by diffusion transfer processing a dye transfer image.
2. Description of Prior Art
As disclosed in U.S. Pat. No. 3,415,644, a composite photosensitive structure, particularly adapted for reflection type photographic diffusion transfer color process employment, which comprises a plurality of essential layers including, in sequence, a dimensionally stable opaque layer; one or more silver halide emulsion layers having associated therewith dye image-providing material which is soluble and diffusible, in alkali, at a first pH, as a function of the point-to-point degree of its associated silver halide emulsion's exposure to incident actinic radiation; a polymeric layer adapted to receive solubilized dye image-providing material diffusing thereto; a polymeric layer containing sufficient acidifying capacity to effect reduction of a processing composition from the first pH to a second pH at which the dye image-providing material is substantially nondiffusible; and a dimensionally stable transparent layer, may be exposed to incident actinic radiation and processed by interposing, intermediate the silver halide emulsion layer and the reception layer, an alkaline processing composition possessing the first pH and containing light reflecting pigment, which may reflect incident radiation, in a quantity sufficient to mask dye image-providing material associated with the silver halide emulsion.
In a preferred embodiment, the composite photosensitive structure includes a rupturable container, retaining the alkaline processing composition having the first pH and light reflecting pigment, fixedly positioned extending transverse a leading edge of the composite structure in order to effect, upon application of compressive pressure to the container, discharge of the processing composition intermediate the opposed surfaces of the reception layer and the next adjacent silver halide emulsion.
The liquid processing composition, distributed intermediate the reception layer and the silver halide emulsion, permeates the silver halide emulsion layers of the composite photosensitive structure to initiate development of the latent images contained therein resultant from photoexposure. As a consequence of the development of the latent images, dye image-providing material associated with each of the respective silver halide emulsion layers is individually mobilized as a function of the point-to-point degree of the respective silver halide emulsion layer's photoexposure, resulting in imagewise distributions of mobile dye image-providing materials adapted to transfer, by diffusion, to the reception layer to provide the desired transfer dye image. Subsequent to substantial dye image formation in the reception layer, a sufficient portion of the ions of the alkaline processing composition transfers, by diffusion, to the polymeric neutralizing layer to effect reduction in the alkalinity of the composite film unit to the second pH at which dye image-providing material is substantially nondiffusible, and further dye image-providing material transfer is thereby substantially obviated.
The transfer dye image is viewed, as a reflection image, through the dimensionally stable transparent layer against the background provided by the light reflecting pigment distributed as a component of the processing composition, intermediate the reception layer and next adjacent silver halide emulsion layer. The thus-formed light reflecting stratum effectively masks residual dye image-providing material retained in association with the silver halide emulsion layer subsequent to processing.
In U.S. Pat. No. 3,415,646, the dimensionally stable layer of the film unit next adjacent the photosensitive silver halide layer or layers is disclosed to be transparent to incident actinic radiation and as disclosed in U.S. Pat. No. 3,415,645, in such instance the light reflecting pigment may be initially disposed in the film unit intermediate the reception layer and next adjacent silver halide layer.
As disclosed in U.S. Pat. No. 3,615,421 of Edwin H. Land, issued Oct. 26, 1971, and U.S. Pat. No. 3,661,585 of Sheldon A. Buckler, issued May 9, 1972, the light-reflecting component of the film unit may optionally be initially disposed as a preformed processing composition permeable layer, intermediate the reception layer and next adjacent silver halide layer, in a concentration which prior to photoexposure is insufficient to prevent transmission therethrough of exposing actinic radiation and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye image-providing material retained associated with the film unit's silver halide emulsion layers, and in U.S. Pat. No. 3,647,435 of Edwin H. Land, issued Mar. 7, 1972, the opacifying component of the film unit may optionally be initially formed in situ, intermediate the reception layer and next adjacent silver halide layer, during photographic processing of the film unit.
In the copending U.S. Pat. applications of Edwin H. Land, Ser. No. 786,352, filed Dec. 23, 1968, now abandoned, and Ser. No. 43,782, filed June 5, 1970, now abandoned, the opacifying component is disclosed to optionally comprise a light-absorbing at the first pH and which may be converted to a substantially non-absorbing species at the second pH, and in U.S. Pat. No. 3,473,925 and the U.S. Pat. Nos. 3,573,042 issued Mar. 30, 1971 and 3,576,626 issued Apr. 27, 1971 of Terry W. Milligan and Richard W. Young, disclosing opacifying and reflecting component, respectively, may be individually interposed intermediate the silver halide layer and reception layer by selective distribution from a composite or a plurality of rupturable containers.
In the U.S. Pat. No. 3,573,043 of Edwin H. Land, issued Mar. 30, 1971, the polymeric neutralizing layer is disclosed to be optionally disposed intermediate the dimensionally stable opaque layer and next adjacent essential layer, i.e., next adjacent silver halide/dye image-providing material component, to effect the designated modulation of film unit's environmental pH; the U.S. Pat. No. 3,576,625 of Edwin H. Land issued Apr. 27, 1971, discloses the employment of particulate acid distributed within the film unit to effect the modulation of the environmental pH, and the U.S. Pat. No. 3,573,044 of Edwin H. Land, issued Mar. 30, 1971, discloses the employment of processing composition solvent vapor transmissive dimensionally stable layers to effect process modulation of dye transfer as a function of solvent concentration.
Where desired, the film unit may also be constructed in accordance with the disclosure of U.S. Pat. Nos. 3,594,165 issued July 20, 1971 and 3,594,164 issued July 20, 1971, both of Howard G. Rogers, to comprise a composite photosensitive structure including a transparent dimensionally stable layer carrying a reception layer, a processing composition permeable opaque layer and a photosensitive silver halide layer and the film unit may include a separate dimensionally stable sheet element adapted to be superposed on the surface of the photosensitive structure opposite the dimensionally stable layer and may further include a rupturable container retaining processing composition and adapted to distribute the composition intermediate the sheet and photosensitive structure to effect processing. As further disclosed in the last-cited applications, in structures wherein the receptor is positioned next adjacent the transparent layer or the processing composition and/or the sheet is to be separated from the remainder of the film unit subsequent to processing, the latter elements may optionally include opacifying component.
As dislosed in the U.S. Pat. No. 3,620,724 issued Nov. 16, 1971 of Edwin H. Land and the copending U.S. Pat. application Ser. No. 3691 of Sheldon A. Buckler, filed Jan. 19, 1970, now abandoned, the dimensionally stable layer referred to may be opaque and in which instance the photosensitive silver halide layer is positioned next adjacent the opaque support layer and the opacifying component of the film unit's processing composition permeable opaque layer will be disposed in the unit in a concentration insufficient to prevent transmission therethrough of exposing actinic radiation and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye image-providing material retained associated with the silver halide layer, and as disclosed in the U.S. Pat. No. 3,647,434 of Edwin H. Land, issued Mar. 7, 1972, the opacifying agent may be optionally formed in such film unit, in situ, during processing of the unit.